Passivation of InGaAs surfaces with an integrated process including an ammonia DECR plasma

Stable and optimum characteristics of micro-optoelectronic devices and circuits require the passivation of the free surface of the III-V materials. An integrated process using a combination of surface cleaning and photochemical dielectric encapsulation is proposed for passivation. The passivation of InGaAs layer has been tempted using a surface cleaning processing in a distributed electron cyclotron resonant multipolar microwave plasma (DECR MMP). In-situ photoemission, ex-situ luminescence and MIS electrical measurements have been utilised to fully characterize the treatment. A substantial increase of surface luminescence signal is observed for an ammonia optimised plasma process. An Auger analysis brought some information about the cleaning mechanism. Namely carbon and oxygen are trapped in a thin gallium nitride film that is formed on the surface. This film can be easily removed from the surface. A UV silicon nitride film is then deposited on this ultra clean surface to stabilise the electronic properties without introducing any more contamination or defects. The resulting C(V) and I(V) measurement made on the protected surface are among the best ever reported for InGaAs surfaces.